LED luminaires are becoming an increasingly popular choice for lighting installations due to their favourable power consumption, longevity and light quality properties, compared with conventional incandescent, cold cathode and gas discharge lighting systems of equivalent specifications. Unlike, for example, incandescent bulbs, which can operate directly from an AC mains power supply, most LEDs require a relatively low-voltage, DC power source. Moreover, because the longevity of LEDs is closely related to the power (voltage and/or current) supplied to the LEDs over time, careful consideration needs to be given to powering LED lighting systems.
It is therefore commonplace for LED luminaires to comprise a light panel, comprising one or more LEDs (connected together in series, parallel, or a combination thereof) and a driver unit that is interposed between an available power supply and the light panel to condition the power to the light panel. In most applications, the driver unit is connected to a switched mains power supply at its input, and to one or more light panels at its output. The driver unit usually comprises a step-down transformer and a rectifier (for stepping-down the mains voltage to a suitable low voltage, and to convert it from AC to DC, respectively), or in certain applications, a more sophisticated inverter is used, which, whilst being generally more expensive than a transformer-rectifier unit, generally offers better control over the output to the light panel, and can improve the quality of the light emitted by the LEDs and/or their longevity.
Given that a driver unit is generally necessary in most LED lighting applications, the end user has two basic choices:
First, a shared driver unit can be used to provide power to a plurality of LED light panels. This option is generally favoured where a number of LED light panels will be relatively closely spaced, and/or where the cabling to the luminaires needs to be “low-voltage” for safety reasons. However, shared driver units result in dual wiring systems being present, i.e. mains wiring to the driver unit, and low voltage wiring between the driver unit and the light panels. Whilst such a system is not uncommon, and in certain cases, desirable, it does increase the likelihood human error when retrofit modifications are made, for example, it is possible to confuse the low-voltage and mains voltage cables.
Second, a dedicated driver unit can be provided for each LED light panel. Such a configuration greatly simplifies installation because only mains wiring is present on site, but incorporating a driver unit into each LED luminaire increases the size and weight of the luminaires, which can make them unattractive. Moreover, because LED light panels have high cooling requirements, it is usually undesirable to co-locate the driver (which generates heat itself) with the LED light panel. Thus, co-locating the driver unit and LED light panel can complicate cooling considerations, especially where passive air cooling is needed. The main commercial drawback, however, of using integrated drivers and LED panels, is that the LED luminaires tend to appear quite “boxy” and unattractive.
One known solution to this problem is provided by the present applicant's FUSION product, upon which the present invention is based. The FUSION product provides a luminaire with separate LED panel and driver housing, which are hingedly connected to one another. The driver unit is located within a hollow interior portion of the hinge and the hinge is IP-rated to withstand the elements. However, it has been found that due to the relative movement of the hinge components, a seal is difficult to achieve and thus the hinge portion is susceptible to filling with rainwater when the unit is used outdoors, or in a submerged installation, meaning that that driver unit can be subject to wet conditions and/or submersion, even when the surrounding environment is dry. Obviously, this can lead to problems over time, such as ingress of water into the driver unit. Moreover, the need for additional sealing of the hinge components can limit the dimensions of the driver, since the driver needs to be accommodated within the hinge. Using an under-sized driver is mostly undesirable because the driver may then need to work at, or beyond, its duty cycle (compared with a larger driver unit). A further problem that is often encountered with known luminaires is that of correctly affixing the luminaire to a surface, such as a wall or ceiling, which operation is often carried out at height, e.g. using a ladder or a “cherry picker”. Because the cabling for a luminaire is usually installed during a “first fix” installation, but the luminaires themselves are installed subsequently, during a “second fix” installation, the installer often has to work with relatively short lengths of cable. However, because one of the objectives of second fix installations is to conceal as much of the cabling as possible from view, the cabling enters the luminaire through the mounting, which means that the luminaire hangs from the wall, by its cable, during installation. A need therefore exists for a luminaire mounting system that provides a temporary, or a secondary, connection between the mounting and the luminaire itself, which permits an installer to use both hands, i.e. without having to support the luminaire with one hand; and/or without simply allowing the luminaire to dangle from its cable during installation of the mount.
A need therefore exists for an improved and/or an alternative LED luminaire, which addresses one or more of the above problems.